Circulatory System

Question 1

Open Circulatory Systems

Answer 1

Mainly in insects/mollusks (don’t contain isolated blood like humans)

Instead, their blood mixes with interstitial fluid (hemolymph)

Blood pumped into hemocoel (internal cavity where organs sit), directly bathes organs with oxygen/nutrien rich hemolymph

hemolymph then returns to heart through holes (ostia)

Question 2

Closed Circulatory System

Answer 2

Found in annelids (i.e. earthworms), mollusks (octopi, squids) and vertebrates

Blood does not mix with interstitial fluid (confined to vesicles)

Question 3

Arteries

Answer 3

Vesicles that move blood away from heart

Branch into arterioles, then capillaries

Question 4

Veins

Answer 4

Vesicles that move blood towards heart

Capillaries—> venules—> veins

Question 5

Contraction/ Relaxation of Ventricle

Answer 5

Contraction causes AV valve to close

Relaxation causes semilunar valve to close

Prevents backflow

Ventricles have thicker walls than atria so they can contract and pump blood

Question 6

Pulmonary Circuit

Answer 6

Blood pwathway between right side of heart, to lungs, left side of heart

Question 7

System Circuit

Answer 7

Circulation pathway throughout the body (between the left and right side of heart)

Question 8

Cardiac Cycle

Answer 8

Rhythmic contraction/relaxation of heart muscles

Question 9

Autorhythmic Cells

Answer 9

Regulates cardiac cycle

Do not need help from nerves (function on their own)

Question 10

Steps of Cardiac Cycle

Answer 10

SA (upper wall of RA) contracts both atria at the same time, sends delayed impusle to AV node

AV node (lower wall of RA), sends impulse through bundle of His, which passes between ventricle, and branches into ventricles via purkinje fibres Causes contraction of ventricles

Ventricles contract (systole) (both AV valves close), blood goes through pulmonary arteries and aorta

Ventricles relax (diastole), small amount of backflow into ventricles causes seminlunar valves to close

Question 11

Hydrostatic Pressure in Heart

Answer 11

Causes movement of blood through arteries

Blood pressure drops and is ultimately 0 in the venules

Blood continues to move through veins (but not due to contractions of heart)

Due to contraction of skeletal muscles which squeeze on veins

Squeezing pushes blood towards heart because veins contains valves to prevent backflow

Question 12

Electrical Conduction

Answer 12

Electrical signals in neurons can travel through gap junctions ONLY in the heart

Question 13

What Conditions Shift Hb Binding Curve to the Right

Answer 13

Low pH (High H+)
High temperature
High CO2
2,3, DPG

Oxygen doesn’t bind as easily to Hb